Tape drive devices for storing magnetic data are well known in the art. In the forward mode, tape is moved from a supply reel, which supplies the tape, to a take-up reel, which draws tape from the supply reel along the tape path and over the magnetic read/write head. In the reverse mode, tape is moved from the take-up reel to the supply reel.
Tape cartridge configurations for data storage generally fall into one of two categories. In the first category, both reels are located inside a single magazine or cartridge, that is, the supply reel and the take-up reel are contained within a single housing. In the forward read/write mode, the tape moves from the supply reel to the take-up reel in a single housing and vice versa in the reverse mode. The read/write head is located in the tape drive separate from the tape cartridge. Examples of such cartridges include quarter-inch cartridges (“QIC”), digital audio tape (“DAT”) cartridges, and audio/video cassettes.
The second category of tape cartridge configurations has only a single reel, generally the supply reel, in the cartridge or magazine. This type of cartridge is used with a tape drive having a take-up reel permanently housed in the tape drive unit. In such tape drives, the tape cartridge is inserted into the tape drive unit. The cartridge is then registered and the front end, or leader end, of the tape is transferred from the supply reel along the tape path of the tape drive to the take-up reel. The magnetic read/write head, which reads or writes to the tape, is located along the tape path and the take-up reel serves to draw the tape across the magnetic read/write head. Examples of such cartridges include DLT (Digital Linear Tape) cartridges made by Quantum, 3480/3490 cartridges made by IBM, and LTO (Linear Tape Open) cartridges to be made by Seagate Technologies, Inc., Hewlett Packard, and IBM.
There are a number of single reel tape cartridges available in the marketplace. Tape drives that work in conjunction with such cartridges have a take-up reel located inside the tape drive housing and should have a suitable tape path for proper tape handling. The tape paths of these tape drives provide many, if not all, of the following features:                a proper wrap angle to the read/write head;        the ability to filter out axial runout of the reels/motors as the tape moves from a reel to the head (i.e., the tape path must move the tape in a reasonably straight path);        minimization of, and the effects of, misalignment between the reels;        minimization of drops in the tape tension along tape guiding elements as the tape travels from one of the reels to the read/write head;        minimization of tape wear at the media surface and at its edges;        operation in a rapid start/stop mode;        minimization of shifting in the tape position when the tape changes from a forward direction to a reverse direction, or vice versa;        a suitable surface under varying humidity and temperature conditions to ensure that the tape does not stick to the guiding elements; and        a suitable surface to conduct electrostatic charges that build up on the tape surfaces.        
To achieve the above features, tape paths generally have a combination of tape guiding elements or members. Examples of these guiding elements include flanged or flange-less guide rollers, fixed guides, and air bearing guides.
One known tape path is disclosed in U.S. Pat. No. 5,414,585, which uses a large number of tape guide rollers to guide the tape along the tape path from the supply reel to the take-up reel. One of the problems associated with this design is the large initial motor current that is required to overcome the mass moment of inertia of the rotating guide elements. As a result, for a rapid start/stop requirement, this device has potential problems.
Moreover, depending on tolerances allowed during fabrication of this type of tape drive, each of the guide rollers may contribute to error in the tape path, rather than eliminate the error. Also, these tape guide rollers use precision ball bearings, which must be lubricated to reduce wear and, subsequently, raise the possibility of failure. The motors in these tape drives also must produce a certain amount of torque to overcome the drag produced by the rollers, thus requiring higher torque motors.
Another known tape drive with its associated tape path is described in U.S. Pat. No. 5,224,641 (also U.S. Pat. No. 4,842,177), in which the drive utilizes air bearing guides as its guide elements. Air bearing guides are advantageous in that they are highly reliable, provide excellent tape guiding, and result in very low stiction. There are problems, however, with air bearing guides because, foremost, they utilize an air pump and must have the necessary plumbing to get the air from the air pump to the air bearing. Modern computers, however, are very constrained with respect to space and tape drives must satisfy a certain form factor. As a result, if the form factor of the tape drive is small, then air bearing guides are not a good solution because of the space required to house the air pump and the associated plumbing elements. In addition, tape drives that utilize air bearing guides are very expensive.
Tape drives having tape paths that utilize only fixed guides are well known in the art, but have many problems. In such tape drives, a well-designed tape path has a maximum length of tape between the supply reel and the take-up reel. Fixed guides produce friction in the tape path, a problem that is considerably more serious in humid environments. Stiction is exacerbated if the angle that the tape must wrap around the fixed guide (i.e., the “wrap angle”) is large and/or if the contact area is large.
One type of fixed guide, or “stationary guide”, has been sold by Seagate Removable Storage Solutions LLC in its tape drives and includes a number of components to form the basic fixed or stationary guide assembly. These components include the guide, the spacer, upper inserts, lower inserts, and finger-locating dowel pins. Although the fixed guide assembly operates effectively, certain improvements may be made to the assembly design. For example, some of the concerns with respect to the fixed guide assembly in the tape drives include the relatively large number of components, the number of fasteners utilized for their attachments, the relatively high overall tolerances that are required, and the relatively high cost of the guide due to the large number of components. Furthermore, the relatively high cost is also a result of the basic guide construction, which employs a ceramic material throughout its entire geometry.
Another concern regarding the fixed guide assembly is the design of the compliant pad-finger spring construction and its mounting. The pad-finger supporting beams have a relatively limited length, producing a higher spring-rate. Furthermore, the unconnected pad-finger supporting beams do not allow for a synchronous mode of the beams. This prevents simultaneous biasing of the tape by the pad-fingers. Also, there is no dampening mechanism for the pad springs, resulting in high excursions of tape motion at a resonance frequency.